51 lines
967 B
C#
51 lines
967 B
C#
namespace Intelix.Helper.Encrypted;
|
|
|
|
public class RC4Crypt
|
|
{
|
|
public static byte[] Decrypt(byte[] key, byte[] data)
|
|
{
|
|
if (key == null)
|
|
{
|
|
return null;
|
|
}
|
|
if (key.Length == 0)
|
|
{
|
|
return null;
|
|
}
|
|
if (data == null)
|
|
{
|
|
return null;
|
|
}
|
|
byte[] array = new byte[256];
|
|
for (int i = 0; i < 256; i++)
|
|
{
|
|
array[i] = (byte)i;
|
|
}
|
|
int num = 0;
|
|
for (int j = 0; j < 256; j++)
|
|
{
|
|
num = (num + array[j] + key[j % key.Length]) & 0xFF;
|
|
Swap(array, j, num);
|
|
}
|
|
byte[] array2 = new byte[data.Length];
|
|
int num2 = 0;
|
|
num = 0;
|
|
for (int k = 0; k < data.Length; k++)
|
|
{
|
|
num2 = (num2 + 1) & 0xFF;
|
|
num = (num + array[num2]) & 0xFF;
|
|
Swap(array, num2, num);
|
|
byte b = array[(array[num2] + array[num]) & 0xFF];
|
|
array2[k] = (byte)(data[k] ^ b);
|
|
}
|
|
return array2;
|
|
}
|
|
|
|
private static void Swap(byte[] arr, int a, int b)
|
|
{
|
|
byte b2 = arr[a];
|
|
arr[a] = arr[b];
|
|
arr[b] = b2;
|
|
}
|
|
}
|